1. Field of the Invention
The invention relates to a gas valve with electromagnetic actuation, in particular to a fuel-injection valve for gas engines, which includes a sealing member which is actuable by way of the armature of a controllable electromagnet between a or each fuel supply and a or each fuel outlet and with at least one closure spring acting on the sealing member.
2. The Prior Art
In conventional gas engines based on the Otto principle, the fuel gas is admixed in the intake line and is then supplied to the cylinders. Control valves and static mixers, for example, are used in this procedure. However, these systems are too unwieldy for systems with electronic fuel injection. Gas nozzles switched by way of magnets and which meter the fuel and produce combustible mixture in the entire supply system have been used. For use in commercial vehicles, and in particular in the case of stationary gas engines, the excessively small throughflow cross-sections in the case of conventional gas valves have made it necessary to bunch together typically up to twelve of these gas valves in order to achieve adequate cross-sections (corresponding to a conventional central injection).
For the purposes of improved controllability, improved fuel use and more advantageous pollutant emission, however, systems are preferred which operate with the so-called multi-point injection or ported-gas admission and which supply each cylinder individually with its combustible mixture by way of separate injectors or valves. In this case, the quantity of gas supplied is controlled typically by way of the differential pressure, i.e., the difference between the supercharging pressure in the gas line and the gas pressure in the cylinder supply. In this case, the valves remain open over the greater part of the intakes stroke and the time control is carried out with respect to individual adaptation of the quantity of gas supplied to each individual cylinder. The valves known at present, however, are unsuitable for use in systems of this type, since they have insufficiently large throughflow cross-sections of at most 4 to 5 mm.sup.2. On the other hand, however, the requirement of a larger throughflow cross-section involves increasing difficulties in achieving the brief and precise actuating times required and the high degree of precision in metering which is necessary. In addition, in the case of large valve cross-sections large and very powerful electromagnets have been necessary until now in order to move the large valve bodies against the action of the closure-spring arrangement and the differential pressure at the sealing member.
The object of the present invention has thus been to provide a gas valve which has--at the same time--a large throughflow cross-section, exact operating and response times as short as possible and a low power consumption and which is also suitable for use in multi-point or ported-gas admission systems and in the case of supercharged engines in particular in the case of gas engines for commercial vehicles or stationary gas engines.